A recorded or recordable recording medium such as a compact disc (CD) or a digital versatile disc (DVD) has been considered to record identification information (ID) peculiar to a recording medium. According to the record thereof, this identification information can be used as an identifier for deciding whether this recording medium is an authentic one or an illegally copied one. Alternatively, this identification information can be also used as an identifier for enjoying various services.
The various services refer to information (contents) that is not particularly related to information recorded or to be recorded on recording medium, that is, music information, information about artists etc. related to music information, image information (still images, moving images), or digital data such as program data which is used in a computer according to circumstances. Of course, it is possible to provide, as contents for service, information that is related to information recorded or to be recorded on a recording medium.